1. Field
One or more embodiments relate to an organic nanofiber structure based on a self-assembled organogel, an organic nanofiber transistor using the same and a method of manufacturing the organic nanofiber transistor. The organic nanofiber structure and the organic nanofiber transistor can be used to manufacture various flexible high performance electronic devices at low cost.
2. Description of the Related Art
Flat panel display devices, such as liquid crystal display devices and organic electro luminescence display devices, include various thin film transistors (“TFTs”) for operating the devices. Recently, much research on manufacturing TFTs using organic semiconductors has been carried out, because TFTs can be simply and inexpensively manufactured and flexible devices can be manufactured using the organic TFTs. In general, organic TFTs include a substrate, a gate electrode, an insulating layer, source and drain electrodes, and a channel layer. The organic TFTs can be classified as a bottom contact organic thin film transistor, in which a channel layer is formed on the source and drain electrodes, or as a top contact organic thin film transistor, in which metal electrodes are formed on a channel layer using mask deposition. Performance of organic thin film transistors may be influenced by field-effect mobility (carrier mobility) and on/off ratio (on/off current ratio). The carrier mobility may vary according to the type of semiconductor, method of forming the thin films (which affects their structure and morphology), the driving voltage and the like.
Recently, much research on organic semiconductor materials for channel layers of organic thin film transistors has been carried out, and characteristics of transistors fabricated using the organic semiconductor materials have been reported. If low molecular weight organic materials such as pentacene are used, transistors may have relatively high carrier mobility and excellent on/off ratio. However, when low molecular weight organic materials are used to form thin films, an expensive vacuum deposition device may be required, and micropatterns may difficult to form. Accordingly, costs for manufacturing organic thin film transistors may be impractical and large area thin films may be difficult to manufacture. Furthermore, stability may be reduced during electrochemical processes.
In addition, when a thin film for an organic thin film transistor is formed using a solution process, the resulting organic thin film transistor may have a disordered intermolecular arrangement and thus well-ordered thin films may be difficult to obtain. As a result, carrier mobility decreases and current leakage on cut off increases, and thus the organic thin film transistor may not be suitable for practical application in an electronic device. Recently, one dimensional (“1D”) nano- and micro-structures of organic semiconductors have become of great interest for application in solution processable organic transistors. The self-assembly of a 1D structure of π-conjugated molecules can provide not only well-ordered molecular ordering, but also lack grain boundaries within active layers in organic thin film transistors (“OTFTs”). Very recently, several research groups have developed 1D organic semiconductors from pentacene derivatives, oligoarene, perylene tetracarboxylic diimide (“PTCDI”) derivatives, hexabenzocoronene and polythiophene polymers as organic semiconductors via solution phase self-assembly.